Gold-catalyzed synthesis of alkylidene 2-oxazolidinones and 1,3-oxazin-2-ones

N-Boc-protected alkynylamines are converted into the corresponding alkylidene 2-oxazolidinones or 2-oxazinones under very mild reaction conditions in the presence of 1-5 mol% of a cationic Au(I) complex. The scope of the reaction is very general, providing the cyclic carbamates in high yield regardless of the substitution at nitrogen and alkyne terminus.